A number of commenters took issue with my claims about Justice Scalia's discussion about thermal imaging devices in Kyllo, and I wanted to blog more about it. I realize that there may be only 4 or 5 readers who actually care about this, but please pardon my geeking out: I spent five years before law school studying mechanical engineering, specializing (near the end) in heat transfer and fluid mechanics, so I'm probably a lot more sensitive to what I take to be Scalia's misstatement. But for whatever reason, it strikes me as an interesting issue.

A number of commenters agreed with Scalia's suggestion that a thermal imaging device tells you the relative heat of various rooms in a house, because hot rooms will mean hot walls, cool rooms will mean cool walls, etc. To be clear, I think that this is often true. That why police might want to use thermal imaging devices, of course; they may ultimately want to collect evidence that might help make a showing about what's hapening inside the the home. Certainly that was the subjective intent of the officers in Kyllo: they wanted to learn something about the inside temperature of the home. But the issue here is physics, not the intent of some narcotics investigators in a particular case, and as a matter of phsyics it seems to me that Scalia's statement is often untrue. The fact that it is often untrue is what I think makes the claim scientifically irresponsible.

For example, imagine a simple two-room house that is being monitored on a very cold day. Imagine we're looking at the house side by side, with room 1 on the left and room 2 on the right. Further, imagine that the walls on the left side of the house (around room 1) are very well insulated, that the walls on the right side of the house (around room 2) are very poorly insulated, and that the house has central heating that pumps an equivalent anount of heat into each room. If the police direct a thermal imaging device at the house, the device will tell them that the exterior of room 1 is relatively cold, but the exterior of room 2 is relatively hot.

Does this mean that the interior of room 1 is relatively cold, and the interior of room 2 is relatively hot? It seems to me that the answer is no — in fact, the opposite is true. In room 1, the well-insulated room, the heat is being kept inside; it is heating the room, not pumping lots of heat to the exterior of the walls. As a result, the room with the cooler exterior will be warmer inside. On the other hand, the poorly insulated room, room 2, will have hotter walls but be colder inside. Now imagine that the homeowner brings a space heater into the poorly-insulated room, room 2, to bring it to the same interior temperature as room 1. The space heater will heat the exterior of the walls around room 2 even more: the exterior walls around room 2 would be significantly warmer than the walls around room 1. But the interior temperature of the rooms would be the same. As a result, the thermal imaging device won't tell the police anything about the relative interior temperature of the rooms; in this case, it will just tell the police about the relative insulation of the walls.

As I said earlier, none of this is necessarily relevant to the constitutional issue. But it seems to me that Scalia's statement about what the imaging device necessarily does is really about what it can often be used to do, subject to a set of assumptions, and he was wrong to dismiss Stevens' point as somehow factually incorrect.

UDPATE: Commenter T. Gracchus has a very good point:

"Scientifically irresponsible" seems a rather agressive dscription. Your case about inaccuracy does nothing to establish that Scalia was irresponsible. In neither post have you given a hint of what you intend by "irresponsible." Do you just mean inaccurate?

Excellent point; the phrase "scientifically irresponsible" was Jim Chen's, and I was interpreting it to mean only "scientifically inaccurate" without the suggestion of a moral wrong that might be associated with the concept of irresponsibility. My apologies if that caused confision.

Most uses of the English language are not precisely literally correct.

It's literally true that a thermal imager only shows you heat at the surface, and that you must deduce what might be inside. But it's also true that a photograph taken through a window (or better yet, a photograph taken through a curtain that blurs the picture) only shows light from the surface of the window or curtain (and only that light which reaches the camera), and that deductions about what is actually in the room may be wrong.

But we don't going around saying "he didn't photograph the inside of the room, he just photographed the light that went through the window and hit the camera".

Claiming that an imager doesn't see inside the house is being literal to a useless degree.

Many Emergency reponders already have CAD drawings of the house. If we could only require, Green Housing heats up, that they keep a BIM dataset for each house, they could know that they are really looking at...

As I briefly mentioned in a comment in your last post, the problem is all information is subject to assumptions. The question is which assumption is more reasonable. Is it that the insulation on the right and left side of the house are comparable or that there is a wide disparity between the two?

I tend to think the former is the more reasonable assumption, so yes, you're right, Scalis'a statement is subject to a set of assumptions. But all information is. All the information coded on the 300 GB of data I have recorded in my Hard Drives is based on the assumptions of a set of rules as to what the 1s and 0s actually mean.

It seems that the more reasonable the assumption the better the information. Similar wall insulation seems like a more reasonable assumption than the construction folks were just random "could be more insulation here and less there."

I suppose the Police Department could pull down the walls and get an insulation rating of the material insulating the walls, but that seems a little extreme, and I'm sure if I devoted some time to it...could be deconstructed as well.

The flaw in your argument is where you say that Justice Scalia somehow dismissed Stevens' point as "somehow factually incorrect". In the lengthy passage I quoted in the last thread, it is quite clear to me that Justice Scalia was well aware of the technical differences between "off-the-wall" and "through-the-wall" measurements. The footnote you quoted does not suggest otherwise. He doesn't say that Justice Stevens was technically incorrect about what precisely is physically being measured.

Justice Scalia's point is that the exterior temperature actually being physically measured does indeed reveal information about the interior of the house. The precise information being revealed may vary based on the technology being used or the specific make-up of the house, but it is nonetheless information about the inside of the house.

Even if the difference between room temperatures in the house is due to insulation as you suggest, that still reveals information about the interior of the house, information that the police would have to get a warrant in order to view with their own in-person eyes. That's the fundamental point Justice Scalia is making.

Your initial post was that Justice Scalia was scientifically incorrect in his footnote. The quote I posted in the other thread shows that not to be true. Justice Scalia was quite familiar with the technical aspects of what was and was not being measured. His point was that the technical distinction was insufficient to make a legal distinction.

That the police may sometimes misinterpret the information from inside the house being conveyed to them through their measurements of the external temperature (wrongly assuming, for example that the rooms are the same temperature outside because one isn't full of growlights instead of because the pot grower used really good insulation in his growroom) doesn't mean they are learning information about the interior conditions of the house.

[OK Comments: Pat, this is the response I posted to your earlier coment: I believe you're confusing two different things. The distinction between "off the wall" and "through the wall" was not about surface radiation vs radiation from inside, but rather about active vs. passive measurement. Stevens was focused on the fact that infrared is passive measurement: it passively measures radiation that automatically emanates from surfaces. In contrast, other devices require active measurement, actually sending electromagnetic impulses to the place to be monitored and then making mresurements based on what happens to those impulses. Scalia rejects the passive/active distinction, but that doesn't address the exterior/interior distinction. That is, you can have passive measurement of the exterior or passive measurement of the interior.]

Scalia to his credit says heat and not temperature. And I think you are neglecting that the thermal images can be collected as a function of time. Because more energy is being radiated from room 2 than room 1, then you know more heat is being put into room 2 than into room 1, or you would see room 2 cool as a function of time. I don't see how you can say this is not information about the interior of the house.

Ultimately this leads into a huge philosophy-of-science quagmire. I could take your argument that the imager only gives information about the exterior of the house and push it a step further: the imager only gives information about the photons entering the imager's scope. From that information we use our knowledge of physics to infer information about the exterior of the house. From that information we infer (or at least get a pretty good guess at) information about the interior of the house.

So, where do we draw the line between what is a "search" of someone's private belongings and what is simply an inference based on knowledge of physics from publically accessible information?

Before this gets attacked as too unusual a case, I want to ask about another specific instance: If you're reading this on a cathode-ray tube monitor, there's plenty of information getting past the front of the screen (where you see it as a picture) and radiating on from there. Someone outside your house can monitor (no pun intended) this and reconstruct what's showing up on your screen. Would you feel comfortable about letting the government look over your shoulder just because it's "only getting information about the electromagnetic field outside the house"?

Similar wall insulation seems like a more reasonable assumption than the construction folks were just random "could be more insulation here and less there."

To the owner of an old house, this assumption is laughable. A typical 100-year-old house has had a couple of additions, several attempts to add insulation and weatherstipping, any of which can be better or worse quality than the original construction. For example, if the room that's lighting up the infrared senser like a christmas tree is a shoddily-enclosed porch, then it makes perfect sense.

As the owner or a 96-year-old house in a town where approx 80% of the houses are at least 75 years old, I question that infrared data rises to the level of probable cause. Or at least probable cause of criminal activity -- I would certainly appreciate it if the cops ring my doorbell and tell me where my house is leaking heat so that I can hire a contractor to put some more insulation in those spots that the insulation contractor missed 50 years ago when they blew in the cellulose...

"Scientifically irresponsible" seems a rather agressive dscription. Your case about inaccuracy does nothing to establish that Scalia was irresponsible. In neither post have you given a hint of what you intend by "irresponsible." Do you just mean inaccurate?

I don't think the initial assumptions you are making are sufficient to draw your the physical conclusions.
If the interior of room A is hotter than the interior of room B, the walls of room A will be hotter than those of room B.
This is because you are assuming the exterior of the house is at a constant, lower temperature. Generally when you solve the diffusion equation you will get a linear dependence for temperature.
Think of it like this:
You have two metal bars stuck into two water sources of different temperature at one end. Both bars are in ice at the other end (keeping the temperature there at 0). The temperature of both bars are linear functions of the distance along the bar (diffusion equation, steady-state). From there you can determine that at some point on the bar, that the temperature will be greater on the bar dipped into the higher temperature than at the corresponding point on the bar dipped in colder water.
The same holds true for rooms, though the function may not be linear, it will still have the same trend.
In essence, the only purpose the insulative effect of the walls play is to determine the different temperatures of the rooms. (This is because we are performing the proper steady-state simplification.)

If you are trying to take into account convection and such issues, that becomes more complicated.

I think perhaps part of the problem is that you are considering it as some sort of dynamical situation considering power sources, when you probably should be looking for a steady-state scenario by considering three heat baths.

The thermal imaging device detects NEITHER the heat of the exterior of the building NOR the heat of the interior of the building. It detects infrared radiation.

Now, it is often the case that certain levels of infrared radiation are associated with certain temperatures of the exterior of the building. And it is also often the case that that certain temperatures of the exterior of the building are associated with certain temperatures of the interior of the building. But NEITHER of those propositions are invariably true.

Orin points out that in some circumstances temperatures of the exterior of the building are not strictly associated with corresponding temperatures of the interior of the building... for example where there is more or less insulation, or where there is heat in the walls.

But Orin fails to point out that in some circumstances levels of infrared radiation are not strictly associated with corresponding temperatures of the exterior of the building either. Like, for example, if there is some infrared emitting device involved.

Now, Orin may quibble about how likely certain circumstances may be (perhaps it is more likely that some rooms have more insulation than it is that there is an infrared emitter). But as a strictly scientific matter, neither Scalia nor Stevens were right.

Even absent some artificial emitter of infrared radiation, thermal imaging depends on TWO variables: the termperatue and the emissivity of the radiating source. If one wall is more emissive than another, then you will get different amounts of infrared radiation in your detector even if the temperature of the two surfaces are the same.

Accordingly, we DON'T know that the exteriors of room A and room B are the same temperature if they show up the same on the thermal imager. That's only true if we assume that the walls have the same emissivity.

I don't think Scalia's statement is wrong. "Information regarding the interior of the home" is dependent, like all transmitted information, on channel conditions. The channel conditions, given which the information about the temperature of surfaces tells us the temperature of rooms, include roughly equal insulation of the rooms, roughly equal emissivity, and other things like that. See Dretske, Knowledge and the Flow of Information (1981); Shannon, A Mathematical Theory of Communication, 27 The Bell System Tech. J. 379-423, 623-56 (1948).

The thermal imaging device detects NEITHER the heat of the exterior of the building NOR the heat of the interior of the building. It detects infrared radiation.

Thermal imaging devices do allow users to "see heat"; in other words, the device translates thermal energy transmitted in the infrared spectrum or wavelength to a visual form. Heat is any thermal energy that an object emits above 0 degrees Kelvin. Absolute zero for example contains no heat energy but 1K would would, albeit a very small amount. Is 1K hot? No, but it emanates heat nevertheless. I'm not sure that Scalia was referring to 1.8 degrees F (1K) in the context of police searches.

I am with you on most of the scientific discussion, but I take issue with this characterization:
"But the issue here is physics, not the intent of some narcotics investigators in a particular case, and as a matter of phsyics it seems to me that Scalia's statement [about relative measurements] is often untrue."

"Often untrue"? I doubt it. I grant your hypothetical, but in an era where cookie-cutter subdivisions are the norm and supposedly follow an established building code, how many houses are going to be built in the rather haphazard manner you suggest? I would suggest that the assumptions Scalia makes are likely to be correct in the vast majority of cases, rather than the hit-or-miss insulation you posit.

Orin,
It looks like you do remember a fair amount of heat transfer, particularly as applied to home heating.

Commenters like Joel B. seem to be taking issue with the idea that one outer wall might have more insulation than others and suggest that one might assume all walls have equal insulation.

In fact the amount of insulation in the walls of a given home can and does vary for a variety of reasons. Here are a few:

Water damage: In my house, the previous owner had permitted the gutters to come away from the roof. Water to infiltrated the outerwalls and damaged the insulation which became quite ineffective in one wall. We replaced that insulation when we had the siding replaced.

Shifting: The owner had also failed to repair a few holes in into the attic which became a haven for squirrels. The squirrel occupants had shifted around to create nests. (We fixed th is.)

More shifting: Blow in insulation can settle over time. For a variety of reasons settling may be more severe in one wall than the other. The result is one wall is poorly insulated; the other well insulated.

Faulty construction: Sometimes, contractors are sloppy and partially compress the insulation batts in some walls, thereby decreasing the effectiveness of the insulation in those walls. (Twenty years ago, this was sufficiently common to warrant comment in HVAC oreinted heat transfer courses.)

Remodeling: Sometimes homes are remodeled. The newer additions often have more insulation than the original construction.

So, all things considered, in real houses, one is fairly likely to find the amount of insulation varies from wall to wall -- just as in Orin's example. (And I'm assuming Orin knows this because he took HVAC courses. )

Orin, thanks for repeating your response, I hadn't seen it on the other thread before I posted.

As far as I've read your initial post, though, the specific statement which you believe to show Justice Scalia's scientific error is his footnote 2 which you quoted. But, as others have pointed out, that footnote is correct, given the inherent limitations and differences between writing for scientists and writing for legal publications. He didn't get it wrong, he was just inadequately scientific about it.

I do not at all read Justice Scalia as disagreeing with Justice Stevens on how the technique works (which is what you necessarily allege in criticizing Scalia for a "scientific" inaccuracy). Justice Scalia's point is that the differences in the external IR levels of the home are caused by differences in the internal IR levels.

Unless there's some external heat lamps shining on the outside siding, the presence or lack of temperature variations on the infrared probe do indeed stem from temperature differences on the inside of the siding. Whether that variation is due to grow lights or insulation is irrelevant, which is precisely Justice Scalia's point. Obtaining ANY information about the interior of the house through technical surveillance not generally used by the average passer-by is a search for 4th Amendment purposes.

Justice Scalia clearly understands that the infrared measurement is only directly of the exterior of the home, because he talks about "inferences". The difference in internal heat levels is inferred from the difference in external heat levels, as noted in the previous paragraph. Here's what Justice Scalia had to say:

As for the dissent's extraordinary assertion that anything learned through "an inference" cannot be a search, see post, at 4—5, that would validate even the "through-the-wall" technologies that the dissent purports to disapprove. Surely the dissent does not believe that the through-the-wall radar or ultrasound technology produces an 8-by-10 Kodak glossy that needs no analysis (i.e., the making of inferences). And, of course, the novel proposition that inference insulates a search is blatantly contrary to United States v. Karo, 468 U.S. 705 (1984), where the police "inferred" from the activation of a beeper that a certain can of ether was in the home. The police activity was held to be a search, and the search was held unlawful.4

Finally, Justice Scalia very clearly does address the exterior/interior distinction, when he brings in Katz.

We rejected such a mechanical interpretation of the Fourth Amendment in Katz, where the eavesdropping device picked up only sound waves that reached the exterior of the phone booth.

There is absolutely nothing in that opinion to show that Justice Scalia misunderstood the science involved. To the contrary, he considered and rejected, as legally irrelevant, all the technical objections and distinctions which Justice Stevens tried to make. He was right on the science, and he was right on the law.

[OK Comments: Again, Pat, I think you're misreading Scalia's opinion. Scalia seems to referring to "inferences" in terms of the lessons of a readout of a device. As Scalia says, that kind of inference is not a search, but nor does the use of an inference make something not a search. So sure, of course Justice Scalia is aware of what inferences are. But my read of his opinion, and in particular footnote 2, is that he doesn't understand that infrared radiation is only surface radiation, and thus that measuring the surface of something does not reveal the temperature of what is behind it.

I have to agree with most other people that you are drawing a pretty arbitrary distinction here.

We are talking about energy inside a house that is emenating out of that house. Whether I put insulation there or not, I am merely making it harder (or easier) for that energy to eminate from my property. The question is whether collecting that energy and attempting to infer information is an illegal search. The objections you put up about the insullation in the house at various parts is merely procedural. Obviously various structural differences inhibit or conceal the rate of energy-exchange throughout the house, and that may make it more difficult for any observer to infer the inside (just like curtains could conceal the light coming out of a window). Nevertheless, they are still attempting to gather information on what is going on INSIDE the room, so it seems appropriate to say that you are looking INTO the house.

To annalogize, suppose an officer used a laser microphone to hear a conversation inside the house. The laser is measuring minute vibrations on the first medium it is hitting, such as a window, and reconstructing those vibrations as sound in the receiver. In fact, the listener isn't recording my actual voice, but the energy eminating from my house in the form of pressure-waves. Now, differences in my house and attempts to conceal from such eavesdropping (insullation, curtains, moving to interior rooms, loud music) may indeed make the amount of vibration drop or otherwise mask the vibrations so that it is impossible to infer a conversation. But that doesn't mean that gathering the vibrations is any different in intent.

It seems to me that with the increased efficiency of data-gathering, we need to understand what is considered fair use emisssions (i.e. open to the police to gather at random) and what is considered so private that even if it has eminated into public space, the coherant energy is still protected from random collection and interpretation. All of that comes down to reasonable expectation of privacy, and I would say that energy (sound, heat or otherwise) leaking out of your house in human-imperceptable ways should be considered as having that expectation of privacy.

")Pete Freans (mail):
The thermal imaging device detects NEITHER the heat of the exterior of the building NOR the heat of the interior of the building. It detects infrared radiation."

I'm sure I am one of the only people here to use an infrared camera regularly. Did anyone mention the effects of infrared reflectivity? In addition to the effects of emissivity,what an Infrared camera see's is not always coming from its apparent source. It may be reflected from another location nearby. Trained thermographers use a lot of judgement and experience when performing infrared surveys and calculating their results.

I think "Scientifically Irresponsible" is an apt description of when a "public authority" makes boldly confident assertions that are not just false, but willfully ignorant. If Scalia had taken to time to crack open a ThermoDynamics textbook he would have known better, but instead he took the all too common route of relying on his own view of common sense and then made an assertion dressed up as a statement of "fact", "A thermal imager reveals the relative heat of various rooms in the home. ", which is PROVABLY untrue.

It is this behavior, where public people with no training in a scientific field make assertions that are provably false, but which "sound right" to the average Joe, that fuels scientific ignorance in this country.

It took me 4 years of work to get my B.S. in Physics - Scalia seemingly decided he was an expert after 4 seconds of thought.

No trained thermographer would ever accept a Infrared scan as being accurate without some other form of independent verification. If the police are targeting a specific home and they notice excessive heat apparent coming off it, they'd be better off looking at the gas, electric or heating oil bills to find to verify the apparent temperature because of abnormal use of energy by the home. As an example, when I worked for an electric utility, meter readers collected bounties by reporting electric cheats. The best method was during the summer months. Air Conditioning units would be whirring away without the meter turning....Or conversely, the AC is off and the meter is whirring away and those Sunlamps in the basement are going full blast during the summer. More than one basement pot farm was noticed that way as well.

Seeing that Scalia wasn't working on a physics project, the fact that there are possible reasons he could have been wrong is hardly the point.

The question in the real world is whether the emissions from a house are likely--really likely, somewhat likely, not at all likely--to provide solid information about the rooms behind them.

Scalia thought it was somewhere up toward really likely. I imagine a bunch of attorneys can think of valid warrants based on something less than the certainty provided by the laws of physics.

If, as one commenter mentioned, the room glowing like it was on fire is a poorly-insulated porch, then it would be obviously a porch, likely, or really likely, depending on the degree of shabbiness, to be poorly insulated. I imagine the cops or warrant-issuing judges could make a judgment.

Do you want to see the law require the standards of no less certainty than the laws of physics provide?

Henry,
I don't think Orin is discussing the intent. Of course the intent is to infer what is inside the house. He is discussing the actual physics involved in relating the temperature of the walls to the heat sources or temperatures of interior rooms.

I don't see how the particular sound you picked is analogous to the heat flux/ temperature one discussed by Scalia. Interpreting meaningful sound (which has spectral content) is just different from measuring a scalar like temperature or a vector like heat flux.

It seems to me a better "sound" analogy would be this:

The police set up measurement equipment on the sidewalk outside of your house and measure the sound intensity using some sort of sound meater. From this, they try to infer both the amount of power drawn by your stereo system and also the room where the stereo is playing.

But even that's not analogous yet. To make the physical problems similar, we need to add a few other unknowsn which "mimic" the effect of thermal insulation on the heat transfer problem.

The police will not know whether any of your windows are are open or shut; nor will they know whether you've installed special sound insulation in some walls. Moreover, you live in an area where some people routinely install sound insulation in some rooms but not others. (Because, as unlikely as this is with sound insulation, that's what actually happens with thermal inusulation.)

Can the police really measure the sound intensity in individual rooms in the house this way?

I have no doubt they could determine what song is playing. The physical problems are different and recognizing the song is just flat out easier!

With all due respect to Profs. Kerr, Bernstein, et al., who otherwise run a fascinating blog, this "what is the most scientifcally irresponsible statement in a judicial opinion" thread is a waste of their time and talent.

This thread seems to boil down to the fact that the judiciary doesn't know as much about science as it thinks it does. I'm sure this is true of most subjects. You could have an equally illuminating discussion of "the most theologically irresponsible statement in a judicial opinion" or "the most bone-headed thing the courts have said about NASCAR." All it would show is that folks should exercise some intellectual modesty when pontificating on matters outside their expertise.

I recognize that this is the conspirators blog and they can write about whatever they damn well please. I wouldn't read it on a daily basis if I didn't find it to be one of the most stimulating things on the web. But this thread is losing its utility pretty quickly.

He criticized Justice Scalia for not understanding or accurately stating the science involved. To do so, however, he is inappropriately using Justice Scalia's legal conclusions as a basis for declaring that Justice Scalia got the physics wrong. But, as I have demonstrated, Justice Scalia did not get the physics wrong, and he did not decide the case based on some erroneous understanding of the physics involved. His point, over and over, was that the physics didn't matter. The thermal scan revealed information about the inside of the house. That's a fact. What inferences about the interior of the house can be drawn from the observations is a different matter. But the external conditions measured by the thermal scan were in fact caused, in part, by conditions inside the house. They conveyed information about the internal workings of the house. Whether that should or should not be considered a "search" is a legal question, not a physics one.

In fact, Justice Scalia recognized the differences and limitations you describe. His point is not that the dissent described the functioning of the equipment incorrectly, but that the physics differences simply do not make a legal difference.

[OK Comments: Pat, I'm afraid I still think you're incorrect, for the reasons I have stated in my two responses to you above.]

But, as I have demonstrated, Justice Scalia did not get the physics wrong, and he did not decide the case based on some erroneous understanding of the physics involved. His point, over and over, was that the physics didn't matter. The thermal scan revealed information about the inside of the house. That's a fact. What inferences about the interior of the house can be drawn from the observations is a different matter.

Maybe I'm misunderstanding, but it seems like you are basically saying that "it doesn't matter if they could reasonably believe that a crime was being committed inside the house. What matters is that they found evidence of a crime after they invented a reason to search it".

The thermal imaging device detects NEITHER the heat of the exterior of the building NOR the heat of the interior of the building. It detects infrared radiation.

Right on. Deducing internal temperature from that requires making some assumptions (or tearing the house apart) -- e.g., all portions of the house have equal insulation, and all outer surfaces have equal emissivity. Maybe that retained heat from the day is equal (brick walls warm up nicely in the summer sun). BTW, IR at these wavelengths won't pass thru glass, so imaging of a window essentially reveals the IR that the glass is radiating from the far side, not anything that you'd see thru the glass with your eyeballs.

Of course, as my late IR expert friend remarked, it doesn't matter to the cops, since they already suspect the occupant, and are just looking for an easy way to get probable cause, and will be before a judge who is no expert. Image the house, find a hot spot, jack up the gain until you see one, and go get the warrant. He said it was often used as a timesaver. You can get electric bills for the neighborhood, single out houses of comparable size and with comparable features, and compare the bills. Or you can just drive by an image it. Show the judge the videotape, or just swear that you saw a hot spot, and that's it.

A similar thing was done at Waco, when ATF wanted to gin up a claim that the Davidians were making meth (years before, a tenant in one of their houses, then torn down, had been arrested for making meth). They had a National Guard aircraft image the main building in IR, and said it showed some hot spots. Sure, the kitchen for one thing. Nevermind that, from what I could find, hot spots are not much use when you're looking for a meth lab.

For long range FLIR imaging (i.e., from an aircraft) there are only two frequency bands usable. At other frequencies, atmospheric moisture blocks or scatters the image.

I wonder if we might analogize the issue to another form of intrusive technology. I'm told you can do a decent job of bugging a room by bouncing a laser off the window. It picks up vibrations of the glass, and thus conversations within, all without entering the house or even stepping on the property.

While working on Waco, at one point we did an infrared imaging session on my Thompson submachine gun. It was interesting watching the barrel quickly heat up! We also found that mylar foil does a perfect job of blocking the IR. Too perfect for camoflage, in fact, since instead of a glowing object you became a black one, and against any background but one that showed as black you stood out nicely. (Other problem: your heat is reflected back to you. I damn near went into heat stroke during the experiment).

I suppose this means that you could seal off a house to detection -- except the mylar has to be outside the walls, and a mylar-encased house might be a little obvious. I suppose the tinfoil layer on insulation reduces the signature somewhat, but since heat is still escaping to the exterior wall, it doesn't prevent a signature.

Orin, maybe I'm missing something. You're a bright guy, and I know I'm a bright guy, so we're probably talking past each other somehow. What precisely do you consider the scientific inaccuracy made by Justice Scalia? Do you believe that he actually misunderstood how the infrared technology in question worked? Do you believe that Justice Stevens accurately characterized how it worked, but Justice Scalia got it wrong?

"I suppose this means that you could seal off a house to detection -- except the mylar has to be outside the walls, and a mylar-encased house might be a little obvious. "

1) Don't need mylar, or (anytother IR opaques material for that matter) If you had hypothetically perfect insulation IN the walls, all heat from inside the house will stay in the house and no infrared from inside the house will show up on an IR scan.

"I suppose the tinfoil layer on insulation reduces the signature somewhat, but since heat is still escaping to the exterior wall, it doesn't prevent a signature"

2) You neglect effects outside the house. If the inside was hypothetically perfect insyulation and no IR escapes from inside, the outside of the house will still heat up to at least ambient temperature, and depending on what time of day and direction, the exteriro will heat up due to sun loading effects(think of touching the sheet metal of a car in the sun, much hotter than ambient temperature.

Well, it's hard to guess what Scalia's state of mind was. But if I had to guess, I suppose I would guess that yes, Scalia didn't actually understand how the device worked. If I had to guess, I would guess that Scalia was mostly basing his perspective on the picture contained in the briefs filed in the case. My recollection is that the briefs included a thermal image of Kyllo's home showing the hot spots, and I gather Scalia looked at the picture of Kyllo's home and saw that the hot rooms were hot (where the heat lamps were) and the cool rooms were cool. He thought the imager gives relative measurements because that's what the picture looks like -- the picture in the briefs turned out to give relative measurements of the temperature of various rooms. So Scalia was describing not what thermal imagers do, but rather what that device did in that case, which Scalia presumably figured must be what these things do generally. Of course, that's just my guess, but I suppose it's my guess.

In any event, I didn't think this was the most important question in the world, just an interesting example of lawyers struggling with science. In my view, all Scalia had to say was that although IR is surface radiation, it can often give possible clues as to interior temperatures, and to him that's enough. That would have been fine. But I read footnote 2 as saying something quite different. If you don't, that's fine, but I read it differently.

"So Scalia was describing not what thermal imagers do, but rather what that device did in that case, which Scalia presumably figured must be what these things do generally. Of course, that's just my guess, but I suppose it's my guess."

Absolutely correct on the last point. Most thermal imagers only give a relative picture of a limited temperature range. The more expensive IR cameras provide temperature measurement capability with the assumption the correct values are set for emmissivity, distance and ambient IR levels. By playing with the last three settings a good thermographer can make an IR picture look like anything he wants.

I guess we'll have to agree to disagree, then. I think the rest of the opinion shows that Scalia did indeed understand the science. Perhaps to be more clear, he should have said in footnote 2 "this termal imager" rather than "a thermal imager". Because this thermal imager did indeed show the relative differences in temperature between the various rooms of the house at issue. It doesn't measure those differences directly, but it does indeed "reveal" them.

But I agree with you that it's an interesting but quite unimportant issue. I enjoy debating such issues; it's a lot more fun then debating more weighty issues. What's the point of blogging if you can't have a little fun every now and then? We've been known to frivol from time to time over at Stubborn Facts ourselves. Thanks for a good-natured debate.

Orin writes: But my read of his opinion, and in particular footnote 2, is that he doesn't understand that infrared radiation is only surface radiation, and thus that measuring the surface of something does not reveal the temperature of what is behind it.

It puzzles me why Orin repeats this error, which I pointed out above.

Thermal imaging devices do NOT measure the temperature of the exterior surface of an object, as Orin seems to believe. Rather, the devices measure infrared radiation.

One must make certain assumptions in order to get from the amount of infrared radiation detected by the machine to the temperature of the object. Among such assumptions is an assumption about the emmisivity of the object, along wth an assumption regarding whether there are any man-made sources of infrared radiation.

These assumptions that Orin is making (and that Stevens made) are no different than the assumptions that Scalia apparently made - that the surface temperature of an object is directly related to the "temperature of what is behind it".

As Orin pointed out, Scalia's assumption may be wrong. But, likewise, Orin's (and Stevens') assumptions may be wrong. If Orin's assumptions turn out to be wrong - for example, if the objects you are measuring with the infrared detecting device have different emissivities - then you may get different readings on the infrared detecting device even if the temperature of the two objects is the same.

Sorry if I am leaving you puzzled. Of course you are right that the device that measures infrared radiation and then converts that radiation in to a corresponding surface temperature actually measures radiation, not temperature. Absolutely. But my approach is simply to take the inferences that we all basically agree on for the sake of argument, and to show that Scalia's further infrerence is not justified. Very good point about emissivity; I like that one a lot. But I'm focusing on Scalia's greater error, not Stevens' lesser one.

Orin, I just checked the previous thread, and noted that I'm being characterized (by you!) as a "living constitutionalist." Well, I am living, and I am a constitutionalist, so I don't deny it.

More to the point, isn't it true that thermometers existed in 1789? And isn't it true that a policeman would generally need a search warrant in order to walk onto private property and measure the external temperature of the house's surface? So, I think Scalia has a point, as an orginalist, that this type of info could not be obtained without a warrant in 1789, and therefore it shouldn't be obtainable in 2006 without a warrant. That would keep the Constitution dead rather than living, no?

Orin, in the case of a house, the surface temperature of the outside of the house depends very heavily on the temperature of the rooms inside the house. Scalia did not say, in scientific terms, that the device was measuring the interior temperature of the house. He said that it was revealing that information. And it was.

As far as I know, there are no colonial-era search and seizure cases (or any pre-1789 English cases) involving thermometers, or merely walking on to property, or even the general category of warrantless search and seizure for that matter. Nor am I familar with any cases in which the government obtained a warrant (or was thought to need one) without actually physically entering a house or physically seizing a person. The cases all involve physical entry, and I dont know of any suggestion in any of the cases that it might involve any kind of non-physical entry.

So as a historical matter, I don't know of any reason to conclude that in 1789 an officer would have needed a warrant to go on property and put a thermometer on a house. So when you ask "isn't it true," I guess I would say, "I don't have any reason to think so."

Of course, this doesn't mean Scalia is wrong, as I don't think Justice Scalia would claim to be a Fourth Amendment originalist. He sometimes tries to link his rules to history, at leats in some sort of way, but I don't think he would claim to be a Fourth Amendment originalist.

But it seems to me that Scalia's statement about what the imaging device necessarily does is really about what it can often be used to do, subject to a set of assumptions, and he was wrong to dismiss Stevens' point as somehow factually incorrect.

Stevens' point, as you quoted it, was that thermal imaging of the exterior of a house gave no information about the temperatures of the interior.

By using the example of a special case:

Further, imagine that the walls on the left side of the house (around room 1) are very well insulated, that the walls on the right side of the house (around room 2) are very poorly insulated, and that the house has central heating that pumps an equivalent anount of heat into each room.

you are attempting to discard the general rule. It seems to me that to discard the general rule - that thermal imaging of the exterior of a house gives information about the relative temperatures of the interior - you must show that in general, thermal imaging of the exterior of a house gives no information about the relative temperatures of the interior.

This is similar to discarding a well regarded medical test as useless because it yields a small number of false positives and false negatives.

I've responded to this point several times, so I don't much see the point in repeating what I have said before, but I'm curious as to how far you would take your reading of Scalia's point. Imagine I am standing next to a house from the public street with my eyes closed and my ears covered, and I note that I have not been vaporized by a nuclear explosion. The fact that I have not been vaporized tells me *some* likely information about the inside of the house. For example, it tells me with quite high certainty that a nuclear bomb has not been detonated inside the house during the time I have been standing there. Do you think that my recognizing that I have not been vaporized by a nuclear explosion would be a "search" according to Justice Scalia? It does seem to tell me *some* information about the likely conditions inside the home.

Orin, in the case of a house, the surface temperature of the outside of the house depends very heavily on the temperature of the rooms inside the house.

Heavily?

Please set up a simple 1 dimensional model describing heat transfer through a wall. Then do a sensitivity analysis to find the effect of varying internal wall temperaure on the external wall temperature. Graph out the effects for a range of insulating values of the wall. Consider typical factors like solar radiation, outdoor wind speed, rain, etc.

I believe after you have done this you will discover the effect of varying the internal wall temperature a few degrees has a "small to insignificant" effect on the external wall temperature.

Of course, "small to insignificant" effect isn't absolutely no effect. But I don't think Orin claimed the conditions in the interior room have no effect on the temperature of the outside wall.

IR (or even direct temperature) measurements of the outer wall temperature give some information about what might or might not be happening thermally in a room.

Loud human screams emmitting from a house give some information about what is going on in a house. (Could be a person screaming; could be a scary movie played on high volume.)

Odors coming out of a house give some information about what might be happening in a house. In all cases, you really can't know until you obtain other information (possibly by searching inside the house!)

I'm not a lawyer, but I think Orins's the point in terms of physics is: IR measurements don't measure the temperature inside the house. The IR measurement is consistent with a wide range of possibilities and include the possibility that the room behind the higher external wall is hotter than that a room behind a colder external wall. Confirming this hypothesis requires additional investigation involving something other than measuring the temperature of the wall.

The possibility of of this "apparent reversal" is not even remote; it can and will occur fairly frequently in homes built using modern construction techniques, experienceing normal maintenance, weather conditions and home heating practices.

Orin, I beg to differ. The area immediately surrounding a house is known as the "curtilage." Trespass on this area has always triggered the Fourth Amendment. The pertinent case is United States v. Dunn, 480 U.S. 294, 300 (1987). Therefore, a thermometer-toting policeman in 1789 would have needed a warrant to measure the external surface temperature of someone's house.

[OK Comments: It's true that Oliver claimed in 1987 that the curtilage concept existed at common law, but I believe that statement is simply false as a matter of histroy. Oliver cites Justice Holmes' opinion in Hester for the view that there was a common law distinction between curtilage and open fields, but a) Hester doesn't actually say that, and b) Justice Holmes' opinion in Hester seems to have essentially invented the "open fields" doctrine out of thin air. In Hester, Holmes states that it was okay to walk on open fields, and says that this was clear going back to the common law, but the only authority he cites is a set of pages in Volume 4 of Blackstone that discusses the elements of common law burglary. In that discussion, Blackstone says that entering into the curtilage of a home can constitute a burglary offense. However, Blackstone doesn't say anything about police procedures, or what police practices were at common law (perhaps because there weren't any police as we think of them today at common law). So my examination of the history is that there really isn't any evidence that common law search and seizure rules incorporated such notions, despite Dunn's claim. Of course, if you know of 1789 or earlier cases or treatises that apply something like the modern open fields doctrine, or give search and seizure protection to curtilage, I would be delighted to know of it; I've been interested in this particular topic for years.]

Lev, does it vary at all? If it varies at all based on interior conditions of the house, then Justice Scalia is correct. Can it under some circumstances? Then the thermal imager reveals some information about the inside of the house.

My point has been that Justice Scalia never claimed, as a matter of physics, that the IR measurements were of the temperature inside the house. He claimed that the measurements "revealed information" about the relative temperatures of the different rooms in the house.

Now whether the information revealed would be sufficient to justify a warrant, or whether the alternative explanations make it hard to figure out exactly what is going on in the house is not material. The exterior temperature actually being measured is affected by the interior temperature, and at least in some cases is quite directly related (hence the common use of IR equipment to analyze homes for sources of heat loss). Thus, pointing the IR device at the house reveals some information about the house which could not be determined by the unaided eye of the police officer standing outside the house.

I've responded to this point several times, so I don't much see the point in repeating what I have said before, but I'm curious as to how far you would take your reading of Scalia's point. Imagine I am standing next to a house from the public street with my eyes closed and my ears covered, and I note that I have not been vaporized by a nuclear explosion. The fact that I have not been vaporized tells me *some* likely information about the inside of the house. For example, it tells me with quite high certainty that a nuclear bomb has not been detonated inside the house during the time I have been standing there. Do you think that my recognizing that I have not been vaporized by a nuclear explosion would be a "search" according to Justice Scalia? It does seem to tell me *some* information about the likely conditions inside the home.

Yeah, and what if Napoleon had had tactical nuclear weapons at Waterloo.

It gives me some information that you have an active imagination when it comes to trying avoid what you were originally discussing, which was thermal imaging devices applied to a specific house, what information if any is "obtained" from that, whether Scalia was completely and totally scientifically wrong when he said information could be obtained about interior temps from the exterior thermal imaging, and whether Stephens was correct when he said no information could be obtained.

What if Harold Godwinson had had tactical nuclear weapons at Hastings.

I'm not the world's leading authority on the meaning of the word "houses" in the Fourth Amendment, but it makes sense to me that the word should at least be construed to include the areas that were subject to the law of burglary at common law, and that includes the curtilage (if Blackstone is to be believed).

For further references, you may have already seen this from Justice Scalia in California v. Acevedo :

"An officer who searched or seized without a warrant did so at his own risk; he would be liable for trespass, including exemplary damages, unless the jury found that his action was 'reasonable.' Amar, The Bill of Rights as a Constitution, 100 Yale L.J. 1131, 1178-1180 (1991); Huckle v. Money, 2 Wils. 205, 95 Eng. Rep. 768 (K.B. 1763). If, however, the officer acted pursuant to a proper warrant, he would be absolutely immune. See Bell v. Clapp, 10 Johns. 263 (N.Y. 1813); 4 W. Blackstone, Commentaries 288 (1769)."

I cannot see why a police officer in 1789 would not have sought a warrant before entering curtilage. It would save him from a charge of burglary.

For example, it tells me with quite high certainty that a nuclear bomb has not been detonated inside the house during the time I have been standing there.

No, it doesn't, because the house may in fact be built as well as the containment vessel for a nuclear reactor and the nuclear bomb that was exploded was of insufficient tonnage to do any damage to house such that the results of the explosion would reach you in any form.

He claimed that the measurements "revealed information" about the relative temperatures of the different rooms in the house.

Pat. I'm trying to figure out if we have a difference of opinion about the meaning of the word "reveals" or a difference of opinion about the physics.

Based on the standard definition of "to reveal", revealing the relative temperatures of the different rooms" is precisely what IR measurements cannot do.

In reality, IR measurements of an outer wall can -- at best-- "give rather ambiguous hints or clues" about the temperature inside a room.

There is no point in trying to make Scalia "correct on the physics" by suggesting that "giving hints or clues" would have been sufficient to support his final conclusion as a matter of law.

Maybe giving hints would be sufficient as a matter of law. (I have no idea. I'm not a lawyer. I'm an engineer.) However, that argument is irrelevant to the question of whether or not Scalia was correct on the physics.

In the paragraph Orin quoted, Scalia was specifically arguing with Stephen's about the physics. Scalia specifically used the word "reveal", not "gives ambiguous hints".

"To reveal" is not an obscure, vague or slippery word. Both "reveal" and "give hints" and their stardard meanings are understood by children in grade school who use them correctly. I would assume Scalia, who is thought to carefully select words, meant "reveal" the way it is defined and not in some mallable Clintoneque "what's the meaning of 'is'" kind of way.

So, it appears
a)Scalia meant to say "reveal" not "give obscure hints about" and
b) he intended to be discussing physics.

He was incorrect on the physics.

As to the legal reasoning -- I have no comment. I am not a lawer.

Lev:

So, is it possible to have cavitation in a compressible fluid?

Strictly speaking the compressibility of the fluid has nothing to do with cavitation.

It is possible to have cavitation in any liquid that can change phase to gas. It occurs when the local pressure drops below the vapor pressure causing the liquid to vaporize.

Most liquids are treated as incompressible when doing most fluid dynamics or hydrostatic problems. So, as a general rule, cavitation occurs only in liquids, which are effectively incompressible.

But my approach is simply to take the inferences that we all basically agree on for the sake of argument, and to show that Scalia's further infrerence is not justified. Very good point about emissivity; I like that one a lot. But I'm focusing on Scalia's greater error, not Stevens' lesser one.

I understand that's what you are doing. My only point was that "the inferences that we all basically agree on" may not, in fact, be inferences that we "all" basically agree on. Moreover, Scalia's further inference may also be an inference that we "all" basically agree upon. Depends on what's menat by "all". Maybe your view as to which inferences are agreed upon differs from mine. And, more importantly, from Scalia's.

In particular, I wouldn't conclude that Scalia's is the "greater error" and Stevens' the "lesser one". Certainly not without some evidence that Scalia's inference is less warranted than Stevens'.

(BTW - cracked open my Thermal Physics volume from college last night just to doublecheck my memory. First time since college. Aaaah, thermal physics... whoever said we didn't have fun in college?)

Stephen's didn't make the "lesser error" AS suggests. Contrary to AS's assertion that Stephens incorrectly stated that IR sensors measure the temperature of the surface, Stephens correctly observed:

All that the infrared camera did in this case was passively measure heat emitted from the exterior surfaces of petitioner's home; all that those measurements showed were relative differences in emission levels, vaguely indicating that some areas of the roof and outside walls were warmer than others.

(Italics mine.)

Stephen's consistently uses the term "heat emmissions" and correctly identifies that this is only "vaguely related" to temperature of the outisde walls and the roof.

This is correct. As AS tells us, the heat emmission wsa the variable measured and it only vaguely related to the temperatures. That means that Stephens is correct!

Lucia, I don't think we disagree about the physics at all. I think we disagree a lot about the meaning and usage of the word "reveal". I don't consider it nearly so concrete a word as you seem to, in the context in which Justice Scalia used it. He did not say that it conveyed the precise details of the interior temperatures. He said it revealed some information about the interior. And it did. Should he have prefaced it with "in some circumstances, a thermal imager reveals..."? That would have been more scientifically clear. But his legal point makes that irrelevant. If there are any circumstances in which using the thermal imager would disclose information to the police about the interior of the house, then use of the thermal imager would be prohibited.

Look at it this way. The device is only useful to the cops if it shows them information about the interior of the house, right? If the heat differences "revealed" are caused purely by external conditions, then the police can't use that to establish probable cause that the homeowner has a growlamp in one room of the house, right? So in each and every instance in which the the thermal imager would provide anything useful at all to the police, it is in fact doing what Justice Scalia said, conveying information about the internal condition of the house.

And keep in mind that, under Scalia's analysis, even information about the amount of insulation in the walls is private information, to which the police are not entitled without a warrant. Stevens said that only "intimate" information was protected, meaning information about the people themselves in the house. Scalia said no, ANY information about the inside of the house, "intimate" or otherwise is protected.

I think you are being overly, deliberately litteral here. First of all, Thermal imaging in regular use has often been used to reveal information about the interior of buildings, including the rellative heat of two different rooms. While you and Orrin have found plenty of cases where the information that is revealed could be misleading or inconclusive, you still have not shown that in fact information isn't being revealed.

A tellescope reveals information about what is going on inside a house also, by collecting light reflected from inside the house and focusing it with a lense so that the observer can get information that was otherwise unavailable to him. Often times that information is of limited use due to opaque obstructions such as curtains. Yet it is still revealing SOME information from inside the house. And I think you would be needlessly mincing words to say that just because there are cases where the tellescope is inneffective or misleading that it doesn't still reveal information about the inside of houses.

The fact is there is energy being released inside the house that has some significance. It impacts and is absorbed by the walls and any other surface, eventually leading to energy being emitted on the other side where it can be detected, recorded and analyzed to provide information about what is happenning inside.

In other words, the detector is still collecting that information and displaying it to the observer.

Infrared radiation is popularly known as "heat" or perhaps "heat radiation," since many physics teachers traditionally attribute all radiant heating to infrared light. This is wrong, and is a very widespread misconception. Light or electromagnetic waves of any frequency will heat surfaces which absorb it. IR light from the sun only accounts for 50% of the heating of the Earth, the rest is caused by visible light. Green lasers can char paper, incandescently hot objects put out visible radiation, and ice cubes emit mostly microwaves. However, it is true that objects at room temperature will emit radiation mostly concentrated in the mid-infrared band (see black body).

No, it doesn't, because the house may in fact be built as well as the containment vessel for a nuclear reactor and the nuclear bomb that was exploded was of insufficient tonnage to do any damage to house such that the results of the explosion would reach you in any form.

But under Scalia's reasoning, which I thought you endorsed, this remote possibility doesn't matter. So at least under your interpretation of what Scalia is saying, it seems that being alive may be a "search" of all places reasonably nearby. Is this silly? Yes, of course; but then it's not my argument, it's yours.

Pat:
Out of curiosity, do you have a dictionary that suggests something can still be unknown or in doubt after it has been revealed?

In anycase, suppose there is such a meaning (which I dispute), that meaning doesn't make any sense in the context of Scalia's footnote number 2. The footnote appears to be a counter argument to an argument set forth in Stephens' dissent.

Stephens dissent said it is possible to draw inferences about the conditions inside the house based on the IR measurements. No one is disputing that. The "suggestive" value of the measurements would presumably be the basis for establishing probably cause. (BTW: My understanding is all evidence used to establish probable cause in some way suggests --rather than reveals-- what might or might not be occuring in the in the location to be searched. The purpose of searching is to collect evidence that reveals the what is actually occuring. Is that entirely incorrect?)

In anycase, when reading Scalia's footnote, I find it extemely difficult to infer Scalia means "suggest" when he says "reveals ...". To draw out further I find it difficult to believe he meant: "The temperature of the inner rooms can sometimes have an effect on the temperature of the outer wall so, in some circumstances, one can infer which room might be hotter than the other."

In fact, to my mind, claiming Scalia used "reveal" to means "suggest" is tantamount to accusing Scalia of being argumentative and idiotic in a way that has nothing to do with misunderstanding physics!

Stephens said the instrument it measured "heat emmitted". Is your concern that the instrument measures emitted heat but that there is some uncertainty because it missed the heat emitted outside the infrared band?

True. Like all instruments IR meters have some inherent uncertainties and it will in fact miss energy outside the IR.

Though, I have to tell you, given the actual temperature of the house -- which I strongly suspect is much lower than the temperature of the sun -- the amount of energy outside the IR band will be much, much, much less than the 50% some might guess based on the Wikipedia article you quote.

Might I suggest you read further, get to the part describing the Plank function. Then assume some realistic temperature for the house walls -- which are not, mind you at the temperature of the sun.

After doing that, calculate the fraction of heat emmitted in the IR range as a fraction of the total heat emmitted. Let me assure you, the fraction will be nowhere near 50%!

The reason that infrared imagers are at all useful is that in the far infrared, most things have about the same emissivity: about 0.85. Whether an object is white or black doesn't much matter: emissivity in the visible spectrum (what makes for whiteness or blackness) doesn't have much numerical relation to emissivity in the far infrared spectrum, which is what matters to infrared thermometers and imagers. In the far infrared, most everything is the same "color".

The main practical exception is polished metal surfaces; those have low emissivity. And the rule, anyway, is only for solids and liquids; gases generally have zero emissivities except in certain frequency bands (which vary from gas to gas). A marijuana-growing room cooled by forced air could be arranged to be invisible to cops' thermal sensors, although it might be detectable by their noses. This is because the wavelengths used by thermal infrared sensors are ones not absorbed by the gases that comprise air; and it is an absolute law that at each frequency, absorptivity is equal to emissivity; so thermal infrared sensors can't detect hot air.

]It occurs when the local pressure drops below the vapor pressure causing the liquid to vaporize. Most liquids are treated as incompressible when doing most fluid dynamics or hydrostatic problems. So, as a general rule, cavitation occurs only in liquids, which are effectively incompressible.

If cavitation occurs when the local pressure of a fluid drops below the vapor pressure causing the liquid to vaporize, then how can a fluid that is a gas cavitate?

But under Scalia's reasoning, which I thought you endorsed, this remote possibility doesn't matter. So at least under your interpretation of what Scalia is saying, it seems that being alive may be a "search" of all places reasonably nearby. Is this silly? Yes, of course; but then it's not my argument, it's yours.

Under Scalia's reasoning, some information about the relative temperatures inside of a house will be determinable from the outside using thermal imaging equipment. Someone in here with the initials OK has been arguing that Scalia is wrong because houses can be built specifically to interfere with if not prevent any information, including any correct information, about relative temperature conditions inside the house from being ascertained at all from outside the house.

Further, that same person with the initials OK argued that the effect of a nuclear weapon detonated or not detonated "somewhere" was meaningful to this discussion.

These things are silly, and some are silly arguments, and they are yours. Live with it.

To the extent you wish to ....revise and extend your remarks...to the effect that Stephens is not correct when he says that thermal imaging equipment used on the outside walls of a house gives no information about temperatures inside the house but is correct to the extent he meant to say that thermal imaging equipment used on the outside of a house does not necessarily give correct information about temperatures inside the house, and to the effect that Scalia is correct when he says that thermal imaging equipment used on the outside of a house gives information about the relative temperatures inside the house but he is incorrect to the extent he

did not

say that such information may be inaccurate for any number of reasons including but not limited to interior construction of the walls, time of day, weather, etc., I could agree with your revised and extended remarks.

If cavitation occurs when the local pressure of a fluid drops below the vapor pressure causing the liquid to vaporize, then how can a fluid that is a gas cavitate?

It can't. Your question was about cavitation in compressible fluids. My "generally" was better suited to capturing the idea that liquids are generally treated as incompressible for the purpose of doing fluid dynamics and static computations. Theh compressibility of liquids is considered when predicting the speed our sound.

In my view, all Scalia had to say was that although IR is surface radiation, it can often give possible clues as to interior temperatures, and to him that's enough. That would have been fine. But I read footnote 2 as saying something quite different.

Footnote 2 said:

The dissent's repeated assertion that the thermal imaging did not obtain information regarding the interior of the home [..] is simply inaccurate. A thermal imager reveals the relative heat of various rooms in the home.

"[Thermal imaging] can often give clues as to internal temperatures." "[Thermal imaging] reveals the relative heat of various rooms."

You find the distinction between those two sentences worthy of consideration for the most scientifically irresponsible passage (or even merely the most scientifically inaccurate)? What, pray tell, constitutes the difference between "gives clues" and "reveals" - not from a legal standpoint, mind you, but from a scientific standpoint?

Or was the distinction between what Scalia said and what you wish he had said merely that you wanted him to preface it with "IR is surface radiation" ? If so, then it is you who are reading into what he wrote the implication that he believes IR is not surface radiation; Footnote 2 in no way states such a thing.

1. Do I think this is worthy of being the most scientifically irresponsible statement?

I never suggested this was the most scientifically inaccurate statement in a SCOTUS opinion. Orin did.

I have been responding to others' statements claiming Orin is wrong because what Scalia says is actually correct and what Stephens says is actually wrong.

As an engineer and not a lawyer, I am unfamiliar with SCOTUS opinions and would hardly be surprised to learn there are other worse errors.

2. You ask "What, pray tell, constitutes the difference between "gives clues" and "reveals" - not from a legal standpoint, mind you, but from a scientific standpoint?"

Thank you for asking me not to address the legal meanings! As a mechanical engineer my training is in heat transfer and fluid dynamics, not law. :)

I already explained what I believe is the difference between the meaning of "gives clues" and "reveal". My distinction is based on a) the dictionary definitions and b) my understanding of the amount of information provided by this measurement based on my knowledge of heat transfer.

"Reveals" is defined as "to make known". If someone was watching a show, heard the master of ceremonies say, "And know, all will be revealed" and then was given only a hint, they would think the master of ceremonies lied.

"Hinting" or "giving clues" provide partial information-- but do not make something known. If the master of ceremonies said "Here's a hint, now guess", you would think that made sense.

In fact, the information in hints can be both ambiguous or deceptive.

This is an important distinction in meaning in this physical problem because, from a scientific point of view the surface temperature of the outside wall (or the radiation emitted) gives only clues, about the interior temperature of (or heat addition to) a room. The clue is not a very good one and it can be highly deceptive. (Notice that in the case, the police also provided evidence from informants and electrical utilities.)

In short: the "relative heat in the rooms" is still unknown based on the measurements; taking a literal interpretation of "reveal" the measurement does not "reveal". It hints.

I'll also answer an underlying question: Am I nitpicking to suggest "Scalia" meant "to make known" when he wrote "reveal"? Could Scalia have meant "hints at" in the footnote?

Maybe some people might use "reveal" to mean "hint" sometimes. After all, people are often imprecise. I'm not a lawyer, so if a lawyer told me Scalia has a reputation for using words imprecisely, I might be willing to believe Scalia meant "hints at".

That said, even if Scalia is often sloppy with his word choice, I would still have a difficult time believing Scalia meant "hints" by "reveals" in that particular footnote.

In the first sentence of his footnote, which you quoted, Scalia is telling us he is specifically disagreeing with Stephens' dissent where Stephens in fact, said that, based on physics, the interior temperature could only be inferred from the outer measurement. That is, Stephen's argument is that the measurement only gives hints.

So, unless Scalia is being absolutely idiotic, he cannot have gone out of his way to write a footnote that translates to "Contrary to Stephens claim that the measurement only gives clues or hints, the measurement actually gives clues or hints!".

If others want to clear Scalia of being scientifically inaccurate by making him sound like a moron, so be it. I prefer to think he doesn't understand the science.

(For the record, my understanding of the rest of Scalia's opinion is the issue Scalia decided to discuss in the footnote is actually irrelevant to the judgement! As a matter of logic, I don't know why Scalia included it. Maybe Scalia felt it was important to set Stephens straight on the science? )

Or was the distinction between what Scalia said and what you wish he had said merely that you wanted him to preface it with "IR is surface radiation"?

No. Scalia's error has nothing to do with any confusion about measuring temperature vs. radiation emitted. From a physical point of view the "hint vs. reveal" issue is related to the "inside/outside" distinction not the "temperature vs radiation" issue.

When I commented on IR vs. Temperature earlier, I was defending Stephens who AS accused of being wrong because Stephens supposedly mistook temperature for emitted radiation. Stephens dissent clearly uses the term radiation.